Importing an image that is 16bit will be automatically asssigned a texture format without alpha support even though it contains an alpha.

Steps to repro:
1. Open attatched project, open 'Scene'

Result:All 8bit images have their alpha recognized(apart from alpha channel PSD, which may be another bug) but 16bit does not, all 16bit textures are RGB formats whereas the 8bit images are RGBA formats
Expected:16bit images with alphas should be assigned a format that supports alphas.

Repro'd in 5.6.0b11 5.6.0f1
Not repro'd in 5.6.0b10